X-ray microanalysis and analytical electron microscopy

SEM of polished sections of mature C3S or P-C2S pastes shows well-defined 

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The hydrated material has been analysed by X-ray microanalysis and analytical electron microscopy. In a 3-day old paste, that formed in situ from alite or belite did not differ significantly in composition from the corresponding product in pure Portland cement pastes (H4). but at later ages Ca/ Si is lower and Al/Ca higher (R25,R26,T44,U 17,U 18,R42). Ca/Si is typically about 1.55, but the value decreases with age and ratio of pfa to clinker. Uchikawa (U20,U17) reported a value of 1.01 for a 4-year-old paste with 40% replacement of cement by pfa. Several of the studies (R25,T44,U20,U 17) showed that the C-S-H was higher in alkalis if pfa was present, but one cannot tell to what extent potassium or sodium apparently present in the C-S-H has been deposited from the pore solution on drying. For material close to the pfa particles in a 10-year-old mortar. Sato and Furuhashi (S92) found a Ca/Si ratio of 1.1-1.2. 

Lyman CE, Newbury DE, Goldstein JI, et al. (1990) Scanning electron microscopy, X-Ray microanalysis and analytical electron microscopy. A Laboratory Workbook. New York Plenum. 

A.D. Romig, C.E. Lyman, C. Fiori and E. Lif-shin, Scanning Electron Microscopy, X-Ray Microanalysis and Analytical Electron Microscopy, Plenum Press, New York, NY (1992). 

Lyman CE, et al. Scanning electronic microscopy and X-ray microanalysis and analytical electron microscopy a laboratory workbook. New York Plemrni 1996. 

Lichtenberger O, Neumann D. Analytical electron microscopy as a powerful tool in plant cell biology examples using electron energy loss spectroscopy and x-ray microanalysis. Eur J Cell Biol 1997 73 378-386. 

Electron microscopy is an efficient microscopy technique that has been extensively used for the material characterization of artistic and archaeological objects, especially in combination with x-ray microanalysis [54], The use of electrons instead of light in these instruments is the basis of the higher resolution ( 9-0.2 nm) and has greater depth of held than LM. Thus, characterization of the finest topography of the surface objects is possible, and additional analytical information can be obtained. Different electron microscopes are currently used in art and art conservation studies scanning electron microscopes (SEM), Cryo-SEM... 

Electron microprobes permit chemical microanalysis as well as SEM and BSE detection, often referred to as analytical electron microscopy (AEM), or electron probe microanalysis (EPMA)56 57. This is because another product of the surface interaction with an incident electron beam is X-ray photons which have wavelengths and energies dependent on element identity and on the electron shell causing the emission. Analysis of these photons can give a local chemical analysis of the surface. Resolution of 1 pm is attainable. Two types of X-ray spectrometer can be employed ... 

An interesting development of analytical electron microscopy, and a potentially very useful one for mineralogical research, has been made by Spence and Tafto (1982,1983). The technique, known as ALCHEMI (atom location by channeling enhanced microanalysis), is the electron analogue of an x-ray technique originally used by Batterman (1969). The theoretical basis of the technique was discussed in Chapter 4, but it is appropriate to summarize that discussion before considering the ALCHEMI technique in detail. 

Fe2-xCrx(Mo04)3 provides a good opportunity for the quantitative, comparison of two analytical techniques - "classical" atomic absorption analysis and x-ray microanalysis. X-ray microanalysis of thin samples using scanning transmission electron microscopy has become an effective quantitative technique in the last few years(86). as opposed to the well-known electron microprobe analyses of bulk specimens(87) ... 

With respect to other major literature on or related to XRE, are chapters in various analytical series and individual books. Two chapters are in the first edition of the famous Treatise on Analytical Chemistry. Comprehensive coverage of X-ray methods absorption, diffraction, and emission is provided by Liebhafsky et al. (1964) in a 90-page chapter in the section on Optical methods of analysis (E. J. Meehan, section advisor). This is immediately followed by the chapter by Wittry (1964) on X-ray microanalysis by means of electron probes. Chapters on relevant topics appearing in the other well known series on analytical chemistry. Comprehensive Analytical Chemistry, are by Beretka (1975) (Analytical applications of electron microscopy) with a brief mention of the XRF-based technique electron probe... 

Optical microscopy (OM), polarized light microscopy (PLM), phase contrast microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and scanning transmission electron microscopy (STEM) are the methods normally used for identification and quantification of the trace amounts of asbestos fibers that are encountered in the environment and lung tissue. Energy-dispersive X-ray spectrometry (EDXS) is used in both SEM and TEM for chemical analysis of individual particles, while selected-area electron diffraction (SAED) pattern analysis in TEM can provide details of the cell unit of individual particles of mass down to 10 g. It helps to differentiate between antigorite and chrysotile. Secondary ion mass spectrometry, laser microprobe mass spectrometry (EMMS), electron probe X-ray microanalysis (EPXMA), and X-ray photoelectron spectroscopy (XPS) are also analytical techniques used for asbestos chemical characterization. 

To get mechanistic information, gravimetric measurements should always go together with metallographic and analytical investigations aimed at the smdy of the morphology and the composition of the corrosion products and the metal in the vicinity of the surface. For this, a scanning electron microscope equipped with an X-ray microanalysis system is particularly well suited. Transmission electron microscopy in conjunction with electron diffraction, and conventional X-ray diffraction methods are also frequently applied. Surface analysis methods such as XPS, AES and SIMS permit the study of the oxide-metal interface and of initial oxide growth. 

Many interesting studies have been published on the effects of a polluted atmosphere on stone with emphasis on the more chemical aspects [39,40,41]. The physical-chemical analytical techniques employed in the study of building materials provide very accurate qualitative and quantitative results on the alterations related to the patina or crust as well as the bulk chemistry of the exposed stone. Scanning electron microscopy (SEM), Electron probe X-ray microanalysis (EPXMA), Fourier-transform infrared analysis (FTIR), X-Ray diffraction (XRD), energy dispersive X-Ray fluorescence, Ion Chromatography, are the most used techniques for the studies of sulphate black crusts as well as to evaluate the effect of exposition time of the sample stone to weathering[42,43]. 

The toxicity of the mineral is such that quantitative characterization of erionite is extremely important. Samples should be characterized by using one or more of the following techniques (1) powder X-ray diffraction, (2) electron probe microanalysis or inductively coupled plasma-mass spectroscopy, (3) scanning electron microscopy equipped with wavelength dispersive spectroscopy (WDS) and/or energy dispersive spectroscopy (EDS), (4) transmission electron microscopy equipped with WDS and/or EDS and selected area electron diffraction, and (5) similar or better analytical techniques. 

Analytical services include optical microscopy, scanning electron microscopy, transmission electron microscopy, electron probe microanalysis, scanning auger microanalysis, electron spectroscopy for chemical analysis, x-ray fluorescence, x-ray diffraction, thermal analysis (DSC, DTA, TGA, TMA) and Micro-Fourier transform infrared spectroscopy. 

Standard laboratory techniques are used to characterize samples for a failure analysis. These techniques include metallography, scanning electron microscopy (SEM), electron probe microanalysis (EPMA), X-ray diffraction (XRD), Fourier transform-infrared analysis (FTIR), and analytical chemistry. 

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